The outside decorations are very impressive, yet harmonized with the church’s structure and thoughtfully applied in places where they have a soothing effect. Above the main entrance there is a wide ornamental field with Karadjordjevic coat of arms in deep relief, placed in its oval centre. In a semicircle lunette above the portal, there is a mosaic representing the church’s patron saint, St. George, portrayed with Karadjordje’s face, slaying the dragon. It was made in Venice, after the drawing by Paja Jovanović.

The inside of the temple is covered in lavish mosaics that greatly contribute to the required representativeness. Marble floor and iconostasis are completely subordinated to the mosaics. The interior decoration lasted for years. The entire area of the mosaic is 3,500 square metres with 40 million various coloured pieces of glass which have 15 thousand different varieties of colour, making the most vivid artistic impression. The entire mosaic has 725 painted compositions, on which there are 1500 figures. Copies from 60 Serbian medieval churches and monasteries had been brought to the St. George church at Oplenac.

The two tombs ion the ground floor of the church belong to the dynasty founder Karadjordje (in the southern apse) and the temple’s ktitor King Peter I (in the northern apse). Below the central dome there is a massive bronze chandelier of 9 m diameter, weighing 1,500 kg. Its inverted crown shape symbolizes lament over the Serbian Empire demise of 1389.

In the crypt, there are 39 tombs with Dečani onyx ledgers. Out of the 20 tombs of the Karadjordjevic Dynasty whose eternal place of rest is in this Mausoleum, two of them belong to rulers: Prince Alexander and King Aleksandar I. Six generations of the Karadjordjevic family have been buried in this church, one of the most important places of Serbian history.